Method of driving multiple chip CCD image sensor

Abstract

In a method of driving an image sensor comprised of a plurality of image sensor chips to sequentially deliver image outputs from the image sensor chips, start signals are initially applied to all of the image sensor chips at the beginning of the drive timing, a shift clock is applied to only each one of the plurality of image sensor chips which is so selected as to deliver an image output, and image outputs are picked up from the individual image sensor chips by sequentially applying shift clocks to selected image sensor chips so as to provide a continuous sensor output signal, whereby no noise is superimposed on the sensor output signal and the quality of images in the image reader, facsimile equipment, OCR equipment and the like can be improved.

I claim: 
     
       1. A method of driving an image sensor comprised of a plurality of image sensor chips to sequentially deliver image outputs from said image sensor chips, comprising the steps of: initially applying start signals to all of said image sensor chips at the beginning of the drive timing;   applying a shift clock for an image output to only each one of said plurality of image sensor chips which is so selected as to deliver an image output;   taking out image output sequentially from the individual image sensor chips by sequentially applying shift clocks to selected image sensor chips so as to provide a continuous sensor output signal; and   applying shift clocks for discharging residual electric charge in each image sensor chip after an image output has been delivered out of the final image sensor chip.   
     
     
       2. An image sensor driving method according to claim 1 wherein the application of shift clocks to other image sensor chips than an image sensor chip so selected as to deliver an image output is stopped. 
     
     
       3. An image sensor driving method according to claim 1 wherein the shift clock applied to each chip has pulses corresponding to the number of pixels of each chip. 
     
     
       4. An image sensor driving method according to claim 1, wherein said start signal is a start pulse or a transfer gate drive signal.